Method for operating a power tool

• US 7,336,048 B2
• Filed: 05/02/2006
• Issued: 02/26/2008
• Est. Priority Date: 05/02/2005
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Lohr, Guenter
• Primary Examiner(s): Ro; Bentsu
• Application Number:
  US11/416,149
• Publication Number:
  US 20060245135A1
• Time in Patent Office: 665 Days
• Field of Search: 318430-434, 318/471, 173/7, 173/181, 173/217, 320/114, 320/127, 320/134, 340/635, 340/636.1, 340/636.12, 361/23, 361/24, 361/25, 361/33
• US Class Current: 318/434
• CPC Class Codes: H02H 7/0833 for electric motors with control arrangements
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: H02J 7/00309 Overheat or overtemperature protection
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence

Abstract

In a method for operating a power tool with an energy accumulator, in particular a rechargeable energy accumulator, which supplies power to an electric drive motor, a clock frequency is generated by an electronic unit, with which a gate of a MOSFET—which supplies operating voltage to the drive motor—is switched on with each cycle, and a switching-off of the MOSFET is carried out within one cycle using different signals, as a function of operating parameters.

Claims

1. A method of operating a power tool with an energy accumulator which supplies power to an electric drive motor, comprising the steps of generating a clock frequency by an electronic unit;

with the generated clock frequency;

switching on a gate of a MOSFET which supplies operating voltage to the drive motor;

carrying out the switching on of the gate of the MOSFET during a cycle of each pulse of the clock frequency;

sensing an electric current from the energy accumulator;

sensing a power loss of an element selected from the group consisting of the energy accumulator, the drive motor, and both;

sensing a temperature of the energy accumulator;

sensing an electric voltage of the energy accumulator;

switching off the MOSFET during the cycle of each pulse of the clock frequency by any of a number of signals depending on different operating parameters which include a maximum permissible electric current, a maximum permissible power loss of the element selected from the group consisting of the energy accumulator, the drive motor, and both, a maximum permissible temperature of the energy accumulator, and a minimum permissible electric voltage.

2. A method as defined in claim 1;

and further comprising reducing a pulse width of triggering signals of the drive motor, when a specified threshold value of an operating parameter of the power tool is reached.

3. A method as defined in claim 1;

and further comprising determining a signal that is proportional to a parameter selected from the group consisting of ohmic losses in the energy accumulator, ohmic losses in the drive motor, and both;

an integrating a power loss that is above permissible losses.

4. A method as defined in claim 3;

and further comprising obtaining a current from the energy accumulator from a current-proportional signal;

converting the current to a signal that is proportional to a square of the current;

calculating a difference between a current value and a threshold; and

integrating the difference with respect to time.

5. A method as defined in claim 1;

and further comprising switching off the drive motor completely when the energy accumulator is discharged.

6. A method as defined in claim 1;

and further comprising not switching off drilling-site illumination until the drive motor is shut off completely.

7. A method as defined in claim 1;

and further comprising using as the energy accumulator a rechargeable energy accumulator.

8. A power tool, comprising an electric drive motor;

an energy accumulator which supplies power to said electric drive motor;

an electronic unit for generating a clock frequency which is applied to a gate of a MOSFET which applies an operating voltage to said drive motor for said MOSFET to be switched on during a cycle of each pulse of said clock frequency;

means for sensing an electric current from said energy accumulator;

means for sensing a power loss of an element selected from the group consisting of said energy accumulator, said drive motor, and both;

means for sensing a temperature of said energy accumulator;

means for sensing an electric voltage of said energy accumulator, wherein with said MOSFET being switchable off during the cycle of each pulse of said clock frequency by any of a number of different signals depending on different operating parameters which include a maximum permissible electric current, a maximum permissible power loss of an element selected from the group consisting of said energy accumulator, said drive motor, and both, a maximum permissible temperature of said energy accumulator, and a minimum permissible electric voltage.

9. A method of operating a power tool with an energy accumulator which supplies power to an electric drive motor, comprising the steps of generating a drive signal by an electronic unit;

with the generated drive signal, switching on a gate of an electronic switching device which supplies operating voltage to the drive motor;

carrying out the switching on of the gate of the electronic switching device during a cycle of each pulse of the drive signal;

sensing an electric current from the energy accumulator;

sensing a power loss of an element selected from the group consisting of the energy accumulator, the drive motor, and both;

sensing a temperature of the energy accumulator;

sensing an electric voltage of the energy accumulator;

switching off the electronic switching device during the cycle of each pulse of the drive signal by any of a number of signals depending on different operating parameters which include a maximum permissible electric current, a maximum permissible power loss of the element selected from the group consisting of the energy accumulator, the drive motor, and both, a maximum permissible temperature of the energy accumulator, and a minimum permissible electric voltage.

10. A power tool, comprising an electric drive motor;

an energy accumulator which supplies power to said electric drive motor;

an electronic unit for generating a drive signal which is applied to a gate of an electronic switching device which applies an operating voltage to said drive motor for said electronic switching device to be switched on during a cycle of each pulse of said drive signal;

means for sensing an electric current from said energy accumulator;

means for sensing a power loss of an element selected from the group consisting of said energy accumulator, said drive motor, and both;

means for sensing a temperature of said energy accumulator;

means for sensing an electric voltage of said energy accumulator, wherein said electronic switching device being switchable off during the cycle of each pulse of said drive signal by any of a number of different signals depending on different operating parameters which include a maximum permissible electric current, a maximum permissible power loss of the element selected from the group consisting of said energy accumulator, said drive motor, and both, a maximum permissible temperature of said energy accumulator, and a minimum permissible electric voltage.